As is well known to those skilled in the art, hydrocarbon fuels and lubricating oils are being formulated, as by addition of various additives, to improve their properties.
The dispersant and antioxidant viscosity index (VI) improvers can be prepared by free radically grafting of OCP polymer with dispersant monomer such as N-vinyl-pyrrolidone and antioxidant such as phenothiazine disclosed in corresponding U.S. application, Ser. No. 641,742.
Such VI improvers are often hazy. Addition of small amount of the polar materials, typically lubricant dispersants, polypropylene glycols, ester-type synthetic oils or plasticizers improve not only clarity but also the performance of the VI improves. It is, thus, an object of this invention to provide an additive system which permits attainment of improved hydrocarbons and lubricating oil VIIs which are clear and have high-performance. Other objects will be apparent to those skilled in the art.